This invention relates to radiographic imaging and, more particularly, to an imaging system for combining a set of component portions of an image to provide a composite image of a subject.
Radiographic imaging systems frequently employ a camera composed of a scintillator which is viewed by a set of photo-multipliers, the field of view of the camera being designated by a collimator. One such camera is described in the U.S. Pat. 3,914,611 which issued in the name of K. J. Stout on Oct. 21, 1975. The subject to be viewed may be smaller than, or larger than the viewing area as set forth by the collimator. For example, in the case of the imaging of a thyroid which has been doped with a radioactive tracer material, the thyroid is smaller than the viewing area of the typical radiographic camera so that the image can be obtained while the subject remains stationary relative to the camera. However, in the event that an image of the entire body of a human being is to be obtained, as is done for obtaining a scan of the skeleton, the subject is substantially larger than the viewing area of the camera so that a relative motion need be introduced between the camera and the subject to provide a scanning of the subject to obtain the complete image.
A problem arises in that, in the past, the relative motion introduced between the subject and the camera, during the scanning of the subject by the camera, has introduced a degradation of the resulting image. The degradation of the resulting image is characterized in some cases as a smearing, and in some cases as a "zippering" effect at the interface between two contiguous portions of the image. While various attempts have been made to compensate for the relative motion, these attempts have not been completely successful in avoiding the foregoing degradation with the result that the displayed image shows a loss of resolution in the case of images produced by the scanning of subjects which are relatively large as compared to the viewing area of the camera.